The Genome of the Sparganosis Tapeworm Spirometra Erinaceieuropaei Isolated from the Biopsy of a Migrating Brain Lesion Bennett Et Al
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The genome of the sparganosis tapeworm Spirometra erinaceieuropaei isolated from the biopsy of a migrating brain lesion Bennett et al. Bennett et al. Genome Biology 2014, 15:510 http://genomebiology.com/2014/15/11/510 Bennett et al. Genome Biology 2014, 15:510 http://genomebiology.com/2014/15/11/510 RESEARCH Open Access The genome of the sparganosis tapeworm Spirometra erinaceieuropaei isolated from the biopsy of a migrating brain lesion Hayley M Bennett1*, Hoi Ping Mok3, Effrossyni Gkrania-Klotsas3, Isheng J Tsai1,8, Eleanor J Stanley1,9, Nagui M Antoun4, Avril Coghlan1, Bhavana Harsha1, Alessandra Traini1, Diogo M Ribeiro1, Sascha Steinbiss1, Sebastian B Lucas7, Kieren SJ Allinson2, Stephen J Price5, Thomas S Santarius5, Andrew J Carmichael3, Peter L Chiodini6, Nancy Holroyd1, Andrew F Dean2† and Matthew Berriman1† Abstract Background: Sparganosis is an infection with a larval Diphyllobothriidea tapeworm. From a rare cerebral case presented at a clinic in the UK, DNA was recovered from a biopsy sample and used to determine the causative species as Spirometra erinaceieuropaei through sequencing of the cox1 gene. From the same DNA, we have produced a draft genome, the first of its kind for this species, and used it to perform a comparative genomics analysis and to investigate known and potential tapeworm drug targets in this tapeworm. Results: The1.26GbdraftgenomeofS. erinaceieuropaei is currently the largest reported for any flatworm. Through investigation of β-tubulin genes, we predict that S. erinaceieuropaei larvae are insensitive to the tapeworm drug albendazole. We find that many putative tapeworm drug targets are also present in S. erinaceieuropaei, allowing possible cross application of new drugs. In comparison to other sequenced tapeworm species we observe expansion of protease classes, and of Kuntiz-type protease inhibitors. Expanded gene families in this tapeworm also include those that are involved in processes that add post-translational diversity to the protein landscape, intracellular transport, transcriptional regulation and detoxification. Conclusions: The S. erinaceieuropaei genome begins to give us insight into an order of tapeworms previously uncharacterized at the genome-wide level. From a single clinical case we have begun to sketch a picture of the characteristics of these organisms. Finally, our work represents a significant technological achievement as we present a draft genome sequence of a rare tapeworm, and from a small amount of starting material. Background infections, such as those with Spirometra erinaceieuropaei, Tapeworms affect the lives of millions worldwide. Of is scarce. those, the debilitating or potentially deadly cysticercosis Compared with more common human-infective tape- and echinococcosis are priority targets for the World worms, S. erinaceieuropaei has an even more complex life Health Organization [1]. The availability of genomes of cycle (Figure 1) involving a minimum of three hosts for the major disease-causing species Echinococcus spp. and completion. Spirometra spp. are found worldwide but hu- Taenia solium have heralded the way for increased re- man infections are most often reported in Asian countries, search progress and new venues for intervention [2,3]. typically China, South Korea, Japan and Thailand, al- However, molecular knowledge regarding rarer tapeworm though several recent travel and migration-related cases of sparganosis have occurred in Europe [4,5]. The infective stage for humans is a motile, secondary larval form known * Correspondence: [email protected] as the sparganum. Infection can occur through the inges- † Equal contributors tion of raw tadpoles, the consumption of undercooked 1Wellcome Trust Sanger Institute, Parasite Genomics, Cambridge CB10 1SA, UK frogs or snakes, or the use of frog meat as a poultice on Full list of author information is available at the end of the article © 2014 Bennett et al.; licensee BioMed Central Ltd. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (http://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly credited. The Creative Commons Public Domain Dedication waiver (http://creativecommons.org/publicdomain/zero/1.0/) applies to the data made available in this article, unless otherwise stated. Bennett et al. Genome Biology 2014, 15:510 Page 2 of 17 http://genomebiology.com/2014/15/11/510 Figure 1 Life cycle of Spirometra erinaceieuropaei. (A) Unembryonated eggs are released and embryonate over 8 to 14 days in water [10]. (B,C) Eggs hatch to release free-swimming coracidia (B), which parasitize copepods (such as Cyclops sp.) and develop into procercoid larvae (C). (D) On ingestion of the copepod by a veterbrate host - such as a tadpole, frog or snake - these develop into plerocercoid larvae, also known as sparganum. The plerocercoid larvae reside in the tissues of these organisms. The larval stage infection can be passed on when the host organism is eaten. (E) Humans become infected by ingestion of a live larva, or in some cases direct contact, such as a poultice of infected frog tissue on the eye. A larva can also infect humans when an infected copepod is ingested. (F) The larva only develops into the adult form in the gastrointestinal tract once it reaches a definitive host, such as a cat or a dog, where eggs are passed in the faeces (A). Curly brackets denote known hosts, though the full extent of the possible hosts and life cycle complexity of this tapeworm species have not been well characterized. Images of S. erinaceieuropaei are guided by the experimental life history photographed by Lee et al. [10]. Source of modified images; snake [11]; frog courtesy of Anant Patel MD; cyclops [12] (Matt Wilson/Jay Clark, NOAA NMFS AFSC); dog [13] (Richard New Forest). open wounds or eyes [6]. However, infections are also larval tapeworm infection that showed migration across the thought to arise through accidental ingestion of infected brain over a 4-year period. By PCR on DNA extracted from copepods from contaminated drinking water or from abiopsysample,weidentifiedthewormasS. erinaceieuro- swallowing water whilst swimming [6,7]. Once the larva is paei, distinguishing it from S. proliferum,ataxonomically inside the human body, its final location appears unre- related species known for its ability to proliferate (with po- stricted - reported sites of infection include the eyes, sub- tentially fatal consequences) in the human host. From a cutaneous tissue, abdominal cavity, spinal cord and brain histological section, we isolated the parasite and produced a [6,8]. Pathology is associated with location; for example, draft genome sequence. We examined the known targets of infections in the brain can cause convulsions or paralysis. drugs in the parasite genome and used this to predict how The worm is usually only discovered during exploratory this parasite would have responded to chemotherapy-based surgery and treated by its subsequent removal [4,9]. treatments. From a large-scale comparison of gene families Infections with S. erinaceieuropaei and closely related across the tapeworms, we identified gene family expansions tapeworms are rare in humans. Pampiglione et al. [7] col- in this cestode, which is the first of its order (Diphyllobo- lated 300 cases worldwide between 1953 and 2003. A re- thriidea) whose genome has been sequenced. These data view of Chinese language articles revealed more cases, over contribute to the growing global database for identifying 1,000 in Mainland China since 1882 [6]. Because these in- parasites and parasite provenance and will serve as a fections occur rarely, clinicians are not likely to consider resource for identifying new treatments for sparganosis. this diagnosis until many other tests have been performed, and usually the worm is only discovered during surgery. Results Infections are even more unexpected in Europe, as there Migrating cerebral lesions indicate sparganosis were only seven reported cases in the literature before A 50-year-old man of Chinese ethnicity was admitted for 2003 [7]. Recent cases of travel- or migration-related infec- investigation of symptoms that included headaches, com- tion in Europe have occurred in the last three years [4,5]. plex partial and tonic-clonic seizures, reported episodes of In this study we describe genome sequencing of a sin- altered smell and flashback of memory and memory im- gle parasite isolated from a 50-year-old male patient pairment as well as progressive right-sided pain. The who presented in the East of England with a debilitating patient had lived in the UK for 20 years but visited his Bennett et al. Genome Biology 2014, 15:510 Page 3 of 17 http://genomebiology.com/2014/15/11/510 homeland often. MRI of the brain revealed an abnor- (Figure 3). Immediately post-operation, the patient was mality in the right medial temporal lobe of high signal given albendazole and is now systemically well. on T2 (oedema) with a cluster of ring-enhancing lesions (Additional file 1). The diagnostic possibilities were of an Molecular identification of the causative agent as S. inflammatory or a neoplastic lesion. erinaceieuropaei The patient tested negative for HIV, tuberculosis, lime DNA was extracted from the formalin-fixed paraffin em- disease, syphilis, coccidioides, histoplasma and cryptococ- bedded worm and PCR and Sanger capillary sequencing cus. A cysticercus immunoblot with patient serum was was carried using primers for cytochrome oxidase c 1 negative. Inflammatory screens for antinuclear and anti- (cox1), the mitochondrial gene often referred to as ‘the bar- neutrophil antibodies and complement (C3 and C4) were code of life’. A consensus sequence from forward and re- normal and the patient was systemically well. C-reactive verse reads was used to search against the EMBL database protein (CRP) level was within the normal range (3 mg/L), using BLASTN, and returned cox1 from S. erinaceieuropaei as was the erythrocyte sedimentation rate (6 mm/h). Com- as a top hit, notably higher than the search result against puted tomography of his chest abdomen and pelvis showed the proliferative S.